We propose in this Letter a holographic model of tachyon dark energy. A connection between the tachyon scalar-field and the holographic dark energy is established, and accordingly, the potential of the holographic tachyon field is constructed. We show that the holographic evolution of the universe with c >= I can be described completely by the resulting tachyon model in a certain way. (c) 2007 Elsevier B.V. All rights reserved.